The present invention generally relates to residential alarms for detecting an adverse condition in a building. More specifically, the present invention is directed to a method and system for providing an improved test system for an adverse condition detector.
Alarm systems which detect dangerous conditions in a home or business, such as the presence of smoke, carbon dioxide or other hazardous elements, are extensively used to prevent death or injury. In recent years, it has been the practice to interconnect different alarm units which are located in different rooms of a home. Specifically, smoke detecting systems for warning inhabitants of a fire include multiple detectors installed in the individual rooms of a home, and the detectors are interconnected so that the alarms of all the detectors will sound if only one detector senses any combustion products produced by a fire. In this way, individuals located away from the source of the combustion products are alerted as to the danger of fire, as well as those in closer proximity to the fire.
In an effort to maintain the effectiveness of the multiple adverse condition detectors positioned throughout a home, such detectors are provided with a manual test switch. Manufacturers recommend that occupants test each of the adverse condition detectors periodically by pressing the manual test switch and observing if the detector produces a perceptible indication that the alarm is operational, usually by sounding an audible alarm and optionally providing a visual signal from a LED. In addition, battery powered models of such detectors include a battery power monitoring circuit that automatically sounds the audible alarm with a unique sound if a low battery power condition occurs.
Unfortunately, lack of maintenance or improper maintenance may not alert the user that the adverse condition detector is inoperative, and consequently it may not respond when the ambient adverse conditions increase to an undesirable level. This can occur when the owner of the detector has not maintained the detector in proper working condition by failing to check the operability of the detector with the manual test switch on a regular basis as suggested.
One reason why owners do not check the operability of an adverse condition detector at regular intervals results from the fact that such detectors produce an alarm that can be extremely annoying or even painful when the user is in close proximity to the detector.
One solution to this problem is embodied in the Tanguay et al. U.S. Pat. No. 6,348,871. In this system, when the test switch is depressed, an attenuated alarm signal is generated by a transducer, such as an audible horn. The attenuated operational alarm signal decreases the output level of the alarm for at least the first two pulses of a series of alarm pulses that define the alarm signal. By reducing the output level of the first two pulses, the user is able to test the alarm at close range without the uncomfortable sound generated at the maximum level for the transducer, and furthermore the user is allowed to become progressively accustomed to the shrill horn sound. This type of system is embodied by the Model FADC available from Maple Chase of Ill. In the Model FADC produced by Maple Chase, the first two pulses of the temporal alarm signal are generated at two-thirds the full voltage, while the third pulse is generated at full voltage.
Although the attenuation of the voltage applied to the piezoelectric horn reduces the volume of the alarm signal when a user is testing the device, a reduction in the voltage applied to the horn can sometimes cause the horn to produce an inconsistent sound in addition to the lower volume. Although the horn may be operating properly at the lower voltage level, an uninformed user many times reached the conclusion after the first two horn pulses that the horn was not operating correctly due to the slightly different sound generated. Thus, although the prior art system was conceptually functional, the occasional misinterpretation of the poor horn quality presented an opportunity for improvement.
Therefore, it is an object of the present invention to provide an improved test feature that allows the alarm indicator or transducer of the adverse condition detection apparatus to be operated to generate an apparently reduced magnitude alarm signal for the initial output pulses while still applying a full amplitude signal to such transducer. Additionally, it is an object of the present invention to reduce the acoustic magnitude of the perceived alarm output to reduce the impact on the user while operating the transducer according to its optimal characteristics, such that a user perceives proper operation of the device.
The present invention provides an adverse condition detector that enables a user to test the detector in close proximity without having to endure a fully operational alarm signal. The detector of the invention includes a control unit coupled to an adverse condition sensor that is operable to detect an adverse condition in an area near the apparatus. When an adverse condition is detected, the control unit generates an alarm signal through an alarm indicator coupled to the control unit. Preferably, the alarm signal has an alarm level and an alarm duration. In one embodiment of the invention, the alarm signal includes a plurality of alarm pulses each having an alarm pulse duration and the alarm level.
The adverse condition detector of the invention further includes a test switch coupled to the control unit that allows the user to activate the test switch to test the operation of the adverse condition detector. Upon activation of the test switch, a test request is received at the control unit indicating the beginning of a test sequence.
Upon receiving the test request, the control unit generates a test signal that is received by the alarm indicator for indicating to the user that the detector is operating correctly. Preferably, the test signal is generated at the alarm level and for a test duration substantially less than the alarm duration. Since the duration of the test signal is less than the duration of the alarm signal, the user is not subjected to the full operation of the alarm signal during the test sequence.
In one embodiment of the invention, the test signal includes a plurality of pulse trains each having a duration substantially equal to the duration of each alarm pulse in the alarm signal. Each pulse train of the test signal includes at least one test pulse. Each test pulse is generated at the alarm level and for a test pulse duration that is substantially less than the duration of the alarm pulse. Thus, the reduced duration of the test pulses as compared to the duration of each alarm pulse enables a user to test the apparatus in close proximity without having to endure a fully operational alarm signal.
In one embodiment of the invention, the first pulse train of the test signal includes a single test pulse, while the second and third pulse trains include an increasing number of test pulses. Thus, when the test signal is generated, the user is presented with an increasing number of test pulses to indicate proper operation of the adverse condition detector. In the most preferred embodiment of the invention, the first pulse train includes a single test pulse, the second pulse train includes a pair of test pulses, and the third pulse train includes three test pulses. However, varying numbers of test pulses within each of the pulse trains is contemplated as being within the scope of the present invention.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. It should be appreciated by those skilled in the art that the use of various types of output transducers and adverse condition detectors can be utilized while operating within the scope of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.